The objective of this work is to identify, clone, and analyze genes which are involved in premalignant and malignant transformation of human colonic tissue in distinct population groups which vary in their risk for and pattern of development of colon cancer. We have established an arrayed library of sequences expressed in a human colon carcinoma cell line and have determined the level of expression of each of the 4,000 members of this library in biopsy tissue of human colon carcinomas, adenomas, and normal mucosa. This has been accomplished through the development and use of a computerized scanning system to digitize, analyze, store, and process the data. Sequences have been identified which discriminate amongst these tissue types, and a smaller subset of the library is being screened for expression in a wider range of tissues. In addition, we have determined that human endogenous retroviral sequences are expressed in the human colon carcinoma cell line HT-29 and that one transcript may have a viral long-terminal repeat (LTR) linked to cellular sequences other than the internal viral gag and pol sequences. Clones of these endogenous viral transcripts will be obtained, the sequence organization analyzed, and the expression of such sequences in human biopsy material will be determined. (Q)